


Forging a New World

by LilGayCunt



Category: One Piece, 僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia
Genre: Alternate Universe - Pirate, Established Relationship, F/F, F/M, Found Family, M/M, Multi, One Piece AU, Pirating, Polyamory, Sailing, Slavery, Sparring, kind of, kirikicchako, momojirou, quirks as devil fruit
Language: English
Status: In-Progress
Published: 2020-12-10
Updated: 2020-12-16
Packaged: 2021-03-10 03:07:29
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 2
Words: 3,375
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27987453
Author URL: https://archiveofourown.org/users/LilGayCunt/pseuds/LilGayCunt
Summary: Yaoyorozu and Jirou find themselves lost at sea together, only to be found by a mysterious Navy ship whose intentions are unclear. Jirou and Yaoyorozu however, are just trying to live to see another day together as they dive into an adventure like no other.(Momojirou focus, featuring Kirikacchako crewmates)(One Piece AU! I don't think much One Piece knowledge is required to understand, as I won't be using any of the characters. Feel free to yell at me in the comments if it doesn't make sense, however.)
Relationships: Bakugou Katsuki/Kirishima Eijirou/Uraraka Ochako, Jirou Kyouka/Yaoyorozu Momo
Comments: 2
Kudos: 12





	1. Lost at Sea

**Author's Note:**

> Hey! Thanks for taking a risk with this crossover-esque idea of mine! If you are familiar with One Piece; you'll have no issues. If not, you still shouldn't have issues! But even so, I've included a quick crash-course below. If I've forgotten anything, or you are confused but dedicated enough to want to understand, comment or dm me or something. I literally am not sleeping b/c I keep thinking abt this fic idea, I'd do anything to talk about it.
> 
> *For this fic I do not intend to use any major One Piece characters that would not just as easily be understood without context.
> 
> *Devil Fruit Powers are much like quirks, but instead are acquired by eating a rare fruit. Every devil fruit user has a krptonite-like weakness to the sea, however, and not every BNHA character has devil fruit powers.
> 
> *The Navy is the military of the reigning World Government. They enforce most of the laws, and hunt down pirates with bounties.
> 
> *Pirates in this universe range from the plundering pirates you are familiar with, to bands of friends who wanted to be free from the shackles of the law. A pirate is not necessarily a bad person, just one who refuses to conform to the (highly suspect and elitist) law.
> 
> *The 'Grand Line' is a geographical line of the world where the ocean behaves unusually, is very dangerous, and is hard to navigate. This is where most notorious pirates sail.

The waves gently lapped at the row boat, seagulls screeching above as they flew for land. Jirou thought it would be a good idea to follow them, if only she had any more energy to row. Yaoyorozu was similarly spent, arms draped over the edge of the dingy boat. She had her shirt wrapped over her face as she dozed off. In any other situation Jirou would lavish over the image of a topless Momo doused in sweat, but knowing they were lost at sea on the grand line put a damper on that thought.

Any second now they could be found by ill intentioned pirates, swallowed whole by a leviathan, or struck but a sudden, unpredictable storm. Jirou had a fighting chance to survive a storm, but Momo had no such chance. If anything happened to the boat, Yaoyorozu would be as good as dead. Like every other devil fruit user, Yaoyorozu would sink to the bottom of the ocean, sapped of all energy as the ocean claimed her. The thought alone brought Jirou to grit her teeth, forcing her aching arms back into position.

She rowed relentlessly. Or as relentlessly as someone can when they already feel dead, were starved, and had enough sweat to fill a wine cellar. The birds were faster, however. She had little chance to ever catch up, but she’d follow as long as possible. Seagulls had the distinct ability to find land; whether by memory or some animalistic instinct. Jirou continued to force her arms to row, row, row.

  
  


Jirou would guess she managed to follow the seagulls for an hour before the last bird had finally faded over the horizon. Her tendons were raw and paper thin now, but, in theory, they were closer to land. That optimism lasted about five seconds as Jirou mused that there was also the chance that the seagulls had just _left_ an island, in fact bringing them further away.

She tossed the oars into the center of the boat, falling backwards against the stern of the dingy. There was nothing else to do but rest now. They had no more food to eat, no direction, and little hope for survival. It’d only been three days since they were cast off the crew; but it felt entirely too short a lease on life. Jirou closed her eyes, silently wishing for land, a savior, anything.

  
  
  


Jirou was awoken when a shadow crossed over her eyes, blocking the sun from piercing her eyelids. She groggily blinked her eyes open, being met with Momo’s concerned eyes, hair curtaining an already sunburnt and speckled face, “You okay?” She murmured quietly, like there was someone who might overhear. 

Jirou just snorted instead, gesturing around to the vast ocean. “Take a guess, babe.”

Yaoyorozu put a finger to her lips, pretending to think. “Hmm… Considering we’re lost at sea… Probably pretty bad.” Jirou rolled her eyes, but couldn’t resist the smile tugging at her lips. It was hard, even in such a bad situation, to feel sad around Momo. “No luck, I’m assuming?”

“There were seagulls a bit ago, I followed them the best I could but…” Jirou shrugged, idly watching the horizon. “Wasn’t really in the best condition to follow them very far.”

Yaoyorozu pursed her lips disapprovingly, “You could have woken me up! I would’ve helped.” Her eyes softened a touch as she whispered, “I don’t like thinking about you working yourself to death just so I can sleep a little, you know.”

They’d been together for a year now, but even now Jirou’s heart did flips whenever Yaoyorozu got sentimental like this. If her cheeks weren’t burnt by the sun, a blush would surely rise up through Jirou. “Y-yeah, you’re right…” Her eyes drew down, sighing deeply. “I’m sorry.”

Yaoyorozu brought Jirou’s chin up, their eyes meeting as she pulled her in for a quick kiss. “It’s okay, I just worry about how little you worry about yourself.” She whispered along Jirou’s lips. Jirou nodded dumbly, utterly transfixed by the intimate moment. Yaoyorozu eyes soft and caring, adorning a slight smirk that held nothing but love. Jirou never had to wonder why she’d follow Yaoyorozu to certain death in moments like this.

A glint on the horizon broke the moment, Yaoyorozu stiffening and gently moving Jirou to the side. Jirou quizzically followed Yaoyorozu’s gaze across the horizon, finally seeing the periodic flashing of a light reflection. “Do you think…?”

“Whatever it is, it’s going to be our only chance.” Jirou said, nerves hardening like steel. “Hopefully it’s a pirate crew that’ll take us in. If it’s the navy…” She grimaced, gripping Yaoyorozu’s forearm.

“Right. We take our chances.” Yaoyorozu’s nerves hardened, as she stood up in the rowboat. She gripped the stern of the boat, and Jirou watched as a portion of the wood was sucked into Yaoyorozu’s hand like a vacuum. She formed a speaking trumpet from the wood, the cone-like device materializing in her other hand.

Bringing the cone up her lips, Yaoyorozu shouted “Please! We’re lost at sea! Please rescue us!” The cone carried her voice across the rolling waves. Considering how gentle the waves were, it was likely whoever was out there could hear their pleas. Jirou attentively watched where she last saw the light.

Everything was silent for a moment, before the light flashed twice in their direction. “I think they see us.” Jirou said in disbelief, her hand finding Yaoyorozu’s.

A ship started to come into view, a skull and crossbones flag, rolling in the wind. Yaoyorozu excitedly squeezed Jirou’s hand. “I think they’re pirates. I think they’re pirates!”

Jirou however, locked her jaw, shaking her head solemnly. “No, check the stern. That’s a Navy admiral’s ship.” And it was. The stern was a solid dark blue, if a little beat up. There had been an attempt to scrub the ship of the engraved navy symbols, as if someone had simply clawed at the wood until they were indistinguishable. Chipped paint lined the side, clearly having written out ‘Marines’ in a past life. This ship was surely a navy ship. Jirou felt her heart sink, as she stood up next to Yaoyorozu. “This might be it for us, Momo.”

“T-They could be pirates that took a navy ship?” Yaoyorozu stammered, stoking a waning hope.

“Or the navy pretending to be pirates.” Jirou answered, resting a hand on the hilt of her blade. “Either way, that doesn’t bode all too well for us. If they’re the Navy they’ll take you for your bounty, if they’re pirates in a navy ship… who knows what they’ll want.” The devil fruit user nodded solemnly, picking up her own blade from the bottom of the boat. 

Yaoyorozu’s eye clouded with doubt, a single thought resting on her tongue for far too long. “I only regret not being able to take you to Wano.” Yaoyorozu blurted, gazing at the Navy ship.

This took Jirou entirely by surprise. “...Wano?” Jirou asked curiously, “Is that where you’re from?” She racked her brain for the location; there wasn’t such a place from the east blue, so maybe it was in the north blue?

“Yes, I was born there. It’s… A beautiful land, but secluded from the world.”

The large navy ship drew near, its shadow casted long along the sea. It was but a few stone throws away, now.

“We’ll go someday.” Jirou promises, squeezing Yaoyorozu’s hand once more. “We’ll take on the entire ship, if we must.”

“HAH? Take us on? We’d obliterate your sorry asses!” A man snarled from the stern of the navy ship, a mere silhouette behind the sun. “To think Ochako convinced us to help you out, too!” He clicked his tongue, uncrossing his arms. The sun sunk behind the ship as it drew near, drawing him into focus. He wore an adorned navy uniform, though sleeveless to reveal a lean musculature. The outfit was brutally white and buttoned, save for the black long pants. Most unusual, however, was his explosive hair, blindingly blonde even without the sun.

“So you _are_ the Navy.” Jirou supplies instead, gripping her hilt. “Pirate flag just for show?” She widened her stance, her sword clicking against the sheath. The navy man grinned wolfishly, dropping into a fighting stance, hands splayed out by his sides.

“I’m worse than the Navy! I’m the Explosive Justice God-King Bakugou!” Suddenly, explosions erupted from his palms in short bursts, like small cannonball blasts. “I can decimate the boat you stand on in just one blast!”

“Ugh, that won’t be necessary, Bakugou.” The voice of a much calmer woman came from the navy ship, the curls of a short bob-cut and round face just peeking over the railing. “If you truly need rescue, moor your vessel along the side here. The least we can do is take you to the next island.” 

Bakugou snarled at her retreating form, “They said they were going to take us on!” He too disappeared further onto the deck of the ship, their argument fading as quick as it had arrived.

Jirou furrowed her brow, trying to decipher their intentions, only to be jolted to attention by Yaoyorozu’s rowing. “Well?” She smirked, beginning to rock the smaller boat towards the naval ship. “Are you going to help me or…?”


	2. Overstepping a Boundary

**Summary for the Chapter:**

> Jirou’s knuckles flared in pain, and she reeled back, shouting in shock. She knew logically that Kirishima was made of flesh and blood, but it had felt like she just tried to pick a fight with a rock. ‘W-What?”
> 
> Kirishima kept that good natured smile, laughing. “I told you so.”

**Notes for the Chapter:**

> TW: Past slavery  
> It is very brief and not really discussed, but its in there all the same.
> 
> I don't intend to make this a prevalent theme, but it really fit with the world-feel of One Piece and made sense to me? I don't know. If it feels forced or like, too dark for no reason let me know. I can always adjust it.
> 
> Otherwise I hope you enjoy!

It didn’t take long for the row boat to be hoisted out of the water and secured along the side of the naval ship. Surprisingly there was only one person doing the hoisting, a shirtless man with flaming red hair seemingly unfazed by the ropework. He only took a second to finish the final knot before heartily greeting them.

“Hey! Glad we could help you guys. My name’s Kirishima!” He had an absolutely radiant smile, akin to a large, intensely muscular teddy bear. 

“Not as glad as us! I’m Yaoyorozu, and this is Jirou.” Yaoyorozu quipped, laughing lightly.

“I guess you’re right!” He laughed back. It was hard to imagine such a kind man to be the crewmate of that absolute bastard child, Bakugou.

“Oy! Kirishima, don’t get soft on them, they’re still pirates. Once the Captain comes back with their bounties we’re going to eviscerate them.” Bakugou glared from an upper railing, eyes sharp as a hawk.

“We don’t know that, Baku-bro.”

“Well…” Yaoyorozu awkwardly laughed, scratching the back of her head.

“We’re pirates.” Jirou confirmed, eyeing Bakugou. “But if you guys aren’t the navy, then you’re pirates too.”

To Jirou’s surprise, Kirishima reluctantly nodded. “That’s a fair point. We aren’t technically Navy anymore.”

“Tch!” Bakugou clicked, but didn’t deny it either. “Those fucking posers doesn’t deserve to have us in their ranks.”

Not many people claimed to be ex-Navy, and fewer still sailed the grand-line. Ex-Navy actively sailing on an Admiral's ship? Unheard of.

Jirou pursed her lips. “So you guys… quit the navy? Or what?”

“It’s a little more complicated, but essentially, yes.” Ochako sauntered from the captain’s cabin, holding a few papers. “I’ve got your bounty pages here.” She faced the wanted posters to the group. Yaoyorozu’s face was sketched, under which the bounty read ‘Wanted Dead or Alive: 500,000 berries’.

Bakugou scoffed at the numbers, “Only 500 thousand? Not worth our time. That's literal chump change.”

“Oh yeah? And what's your bounty?” Jirou glared, crossing her arms.

Bakugou’s grin grew sharp, “40 million berries. I know your brain might be too small to comprehend but-” 

Ochako’s burning gaze stopped the snide comment, instead Bakugou just rolled his eyes.

“ _ Anyway _ , the bounty isn’t really what I care about. I care about what you were charged with.” Ochako flipped to a new page, reading aloud. “Yaoyorozu is wanted dead or alive for her escape from a noble trading vessel.”

Yaoyorozu just watched Ochako without blinking. 

“The Navy doesn’t care much for traders, you know.” Ochako continued. “They really only care if it's for the nobility of other nations. Or, perhaps, at the beck and call of the Celestial Dragons.” Ochako met Yaoyorozu’s eyes. “Tell us about that.”

Yaoyorozu brushed a strand of hair out of her face, face beginning to contort at the memories. “They wanted to make a slave of me. Some pirates came and I took the chance to escape. I’m not sure there's much else to tell.”

“The Navy doesn’t take slaves.” Kirshima thought out loud, “So the Navy isn’t ‘They’, is it?”

Yaoyorozu silently shook her head, lips sealed.

“I can hardly blame you for that.” Ochako concluded, her form relaxing subtly. “None of us here would. Surprised they cared enough to put a bounty on you, though” Bakugou was silent, decidedly watching the horizon.

“They said I was exotic, so I suppose I was worth a lot.” Yaoyorozu said monotone. Ochako shook her head, tucking the papers away. Kirishima instead bore a look of shame, eyeing the Navy crest engraved in the base of the mast.

“Don’t worry, I won’t be questioning you further on that. I trust you are telling the truth, and I won’t force you to relive it.” Ochako silently looked Kirishima in the eye, who nodded back briskly. She then turned to Bakugou, who bobbed his head after a moment. She continued, “Since neither of you have significant bounties that would lead us to distrust you… Welcome to our ship, The Buoyant Cloud.”

Ochako held her hand out, which Jirou was much too shocked to shake. “Th-That’s it? You guys seriously trust us?”

“Trust might be a stretch,” Kirishima admitted. “But I doubt you guys would kill us in our sleep or anything.”

“And you guys surely would die without us, so…” Ochako trailed off, shrugging the entire matter off lightly. Bakugou seemed ambivalent by now, yawning like his desire for justice had burned off.

“Oh!” Yaoyorozu seemed to break out her own sense of shock, bowing deeply. “Thank you so much! We won’t be a bother, I promise!”

Without any other real options, Jirou had to accept the unreal circumstances. She bowed along with Yaoyorozu, and life on The Buoyant Cloud began.

It was a strange few days following, to say the least. Jirou and Yaoyorozu were both moved to a spare bedroom in the hull. Despite having three crew members living on board, the several bedrooms in the hull were completely empty and unused. 

The unused rooms began to make more sense when Jirou noticed Kirishima dragging a sleepy Bakugou out of the captain’s room for a morning spar. The two would spar on the deck at ungodly hours, Ochako joining later in the day. 

Bakugou leaped forward, propelled by small explosions (which had to be a devil fruit power of some sort), delivering blow after blow to Kirishima. But Kirishima stood strong, taking each hit without flinching. Bakugou used an explosion to flip over Kirishima’s head, attempting to land a kick against his back. Instead, Kirishima swiftly shifting his leading foot back, deftly driving his elbow into Bakugou’s torso.

Bakugou flew along the deck, skidding as he went. He began to wheeze, completely winded by the single hit.

It was the second time that Jirou had watched the two spar, and it seemed to be a particularly exhausting day. Bakugou was heaving on the deck, hands still smoldering from the flames.

“How do you do that?”

Kirishima looked up, still doing a post-workout stretch. “Do what?”

“Not like… die.”

He chuckled at that, saying “It’s my specialty. I’m the best at hardening haki.”

Jirou never prided herself on being particularly smart, but since sailing the grand line it was becoming very obvious how little Jirou actually knew about the world. Like, what in the world was haki?

“What’s haki?”

Kirishima hummed, tapping his chin. “You know how working out improves your muscles? Haki is like that, but for your mind and your spiritual energy.”

Jirou raised an eyebrow skeptically. “No offense, but there's no way that's real.”

Bakugou snorted from the deck in disbelief. 

Kirishima for his part, smiled good naturedly. “I can show you.” He widened his stance a little in a defensive pose, motioning Jirou to make a move. 

“Come on, strike me.”

Jirou had her doubts, but she figured the man could take a fist from her, with or without magic spirit powers. Jirou got into an acceptable fighting stance, steeling her nerves for combat. She quickly threw a jab at Kirishima’s guard and-

“Fuck!”

Jirou’s knuckles flared in pain, and she reeled back, shouting in shock. She knew logically that Kirishima was made of flesh and blood, but it had  _ felt _ like she just tried to pick a fight with a rock. ‘W-What?”

Kirishima kept that good natured smile, laughing. “I told you so.”

“Kirishima’s a fucking beast, and don’t you forget it.” Bakugou snarked from the deck, face still down, wheezing.

“He’s definitely one of the strongest men to sail these seas.” Ochako muses, walking over from the cabin. “He turns into putty with the right touch, however”.

Jirou held back a laugh as Ochako winked at her, Kirishima sputtering in the background. “W-Whatever, I’m allowed to be soft for my girlfriend! What’s more manly than that?”

“Not holding back when you spar your girlfriend?” Ochako said, smirking. “Stop pulling your punches, babe.”

“Yes  _ mom _ .” Kirishima sighed, bringing his fists up.

“Thought that stayed in the bedroom?” Kirishima's mouth gaped open like a fish, but was quickly cut down by Ochako’s fist. Jirou had yet to see Kirishima bleed, even on his worst days. It seemed he didn’t bleed even when caught off guard, he just grit his teeth harder against the attack, apparently only shocked by the attack.  


Kirishima handily won by the end. Despite Ochako’s greater speed, and strength that rivaled Bakugou, her defense eventually cracked with exhaustion. The morning spars were finished with two successive blows, completely throwing Ochako off balance. She landed with a sickening crack against the wood, Jirou eyes widening.

“Ochako are you okay?!” Jirou rushed to her side, missing how neither Kirishima or Bakugou made a move.

“Yeah, yeah. I’m fine.” Ochako pushed Jirou away, clutching her head. “I’ve taken worse, believe me. I’m not made of paper.” 

She huffed, eyes hardening as Jirou continued to examine Ochako’s head determinedly. “Seriously, Jirou. Get the fuck off me, thats an order!”

Jirou was almost too shocked to react, but quickly backed off at that, looking at Kirishima questioningly. He just shook his head silently.

Had she struck a nerve of some kind? Maybe she had overstepped some boundaries? “Yeah that's uh… probably true.” She bit her lip hesitantly, “I’m going to go do…”

“Cargo needs sorted.” Bakugou supplied, not quite meeting Jirou’s eyes.

“Yeah, the cargo. I’m going to do… that.”

The cargo, in fact, did not need sorted. Everything seemed to be sorted and tied down. Maybe Bakugou just wanted Jirou to double check it? Jirou started to look over, her confusion growing. Everything was very precisely, and very neatly put together. Whoever did this last had an eye for detail, there really was nothing-

Bakugou’s boots could be heard stomping down as he approached Jirou, pinching his brow. “Don’t bother. I sorted out cargo yesterday. I was just giving you an out.”

“Right. I knew that.” Jirou said, shutting a crate.

“Look, I know you didn’t mean shit up there. But Uraraka doesn’t take that shit kindly.” He sighed, running his hand through his hair, uncomfortably watching a porthole. “She spent the better part of her entire career having to convince stuffy old white guys that she was stronger than all of those fuckers, and then spent the other half defending her spot.”

That… made sense. If Jirou was being honest, she probably was underestimating her. It was hard to imagine Ochako side-by-side with Bakugou and Kirishima, nonetheless in a high naval position. “Don’t treat her like she’s weak, because she’s not.” Bakugou clipped, eyeing Jirou. “I like you, so I’d hate to blow you up with the rest of your remains. We clear?”

Jirou gulped, gripping the crate behind her. “Crystal.”

“Good.” He nodded, turning around. “By the way, Kirishima says your punch was the weakest thing he’d ever felt, and since you watch our morning spars anyway…” He grinned wolfishly from around his shoulder. “Be up by sunrise, Ears. I’m gonna be beating the shit out of you.”

**Notes for the Chapter:**

> Sorry Yaoyorozu wasn't as prevalent in this chapter; I wanted to develop the versions of these versions of these characters more, and even just those three were difficult to do. More momojirou next chapter, promise! <3

**Author's Note:**

> Someone actually read this self-indulgent idea? Colour me astonished. Thank you so much for reading!


End file.
